CVX error, Invalid constraint: {concave} == {real affine}

I receive such a error information: Invalid constraint: {concave} == {real affine} for the code below

    cvx_begin sdp
    variable W(Nt,Nt,K) hermitian;
    variable nor(1,K);  
    subject to 
    for k=1:K 
    h(:,k)'*W(:,:,k),W(:,:,k)-inv_pos(nor(k))] == hermitian_semidefinite(Nt+1);
   [W(:,:,k), W(:,:,k)h(:,k); 
    h(:,k)'W(:,:,k),inv_pos(1-nor(k))] == hermitian_semidefinite(Nt+1);  
    W(:,:,k) == hermitian_semidefinite(Nt);

It seems that the use of inv_pos introduces convex expression and consequently causes the mistake. Do anyone knows how to solve the problem or rewrite this constrait?

FAQ: Why doesn’t CVX accept my problem? [READ THIS FIRST]

You might be able to change variables. Instead of using nor(k), create a new variable that is equal to 1/nor(k). Call it nori(k). Then you need only ensure that nori(k) is greater than or equal to 1. Of course, if your objective function involves nor(k), you may be stuck.

Thanks. But how if I also have a constraint: [W(:,:,k), W(:,:,k)*h(:,k);
h(:,k)’*W(:,:,k), inv_pos(1-nor(k)] == hermitian_semidefinite(Nt+1); There are same problems when I try to express inv_pos(1-nor(k)) with 1/nor(k).

I’m not sure there is anything to be done.